Hey guys I have a 91 350SDL and about a month ago the battery started dying and I determined that the alternator voltage reg was bad. Since I was on Christmas break at the time the car didn't really get driven much after that for about 3 weeks. Ever since the change I've noticed the car hasn't seemed to be starting right and last week i went to start the car after not driving it for 2 days and it was almost completely dead. The battery is good, its from the dealer and barely a year old. I changed oil last weekend and decided to put the meter on the battery and found out its drawing between 670mA-690mA yikes! If i drive the car everyday I'm good until i went out to start it this morning and it was really hesitant so its getting worse. Its my daily driver to university so i won't be able to work on it until this weekend. Anyone have any ideas where to start? Im not the best with electrical diagnosis so any and all help in finding this short is appreciated.

First thing I'd do is put a battery disconnect in it so you can at least have a driveable car and can fix it at your leisure. Those switches cost maybe $10 and can be installed in a few minutes. Once I started diagnosing, I'd put the meter between the +post and the positive cable to measure draw and remove the fuses one by one until I found the circuit that was causing the draw.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13